Spin–orbit torque driven by a planar Hall current
Spin–orbit torque driven by a planar Hall current
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DOI：
10.1038/s41565-018-0282-0
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发表时间：
2017-12
影响因子：
38.3
通讯作者：
C. Safranski;E. Montoya;I. Krivorotov
中科院分区：
文献类型：
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作者：
C. Safranski;E. Montoya;I. Krivorotov
铁磁金属和非磁性金属多层膜中的自旋轨道力矩(SOT)可以有效地控制FM层的磁化强度。例如，这被用于用于节能移动电子设备的非易失性磁存储器，以及用于神经形态计算的自旋扭矩纳米振荡器。最近，自旋扭矩纳米振荡器也被用于微波辅助磁记录，这使得超大容量硬盘驱动器成为可能。大多数SOT器件采用自旋霍尔效应和拉什巴效应，它们分别起源于NM层内的自旋轨道耦合和FM/NM界面上的自旋轨道耦合。最近，人们预测并实验实现了FM/NM/FM多层膜中由反常霍尔效应产生的SOTS。还证明了SOTS是通过晶体对称性来控制的。了解磁性多层膜中可能出现的所有类型的SOT，是形成全面的SOT理论和工程实际SOT器件所必需的。在这里，我们证明了在FM中引起各向异性磁阻(AMR)和平面霍尔效应(Phe)的自旋极化电流还可以在NM1/FM/NM2多层膜中产生具有反常角对称性的大的抗阻抗SOT。这种效应可以用最近提出的磁子机制来描述。我们的测量表明，在自旋霍尔和拉什巴扭矩都可以忽略的多层膜中，这个扭矩可能很大。此外，我们还演示了由该SOT驱动的自旋扭矩纳米振荡器的工作原理。这些发现极大地扩展了展示巨型SoT的材料类别。
Spin–orbit torques (SOTs) in multilayers of ferromagnetic (FM) and non-magnetic (NM) metals can manipulate the magnetization of the FM layer efficiently. This is employed, for example, in non-volatile magnetic memories for energy-efficient mobile electronics,and spin torque nano-oscillators, , , –for neuromorphic computing. Recently, spin torque nano-oscillators also found use in microwave-assisted magnetic recording, which enables ultrahigh-capacity hard disk drives. Most SOT devices employ spin Hall,and Rashba effects, which originate from spin–orbit coupling within the NM layer and at the FM/NM interfaces, respectively. Recently, SOTs generated by the anomalous Hall effect in FM/NM/FM multilayers were predicted and experimentally realized. The control of SOTs through crystal symmetry was demonstrated as well. Understanding all the types of SOTs that can arise in magnetic multilayers is needed for a formulation of a comprehensive SOT theory and for engineering practical SOT devices. Here we show that a spin-polarized electric current known to give rise to anisotropic magnetoresistance (AMR) and the planar Hall effect (PHE) in a FM can additionally generate large antidamping SOTs with an unusual angular symmetry in NM1/FM/NM2multilayers. This effect can be described by a recently proposed magnonic mechanism. Our measurements reveal that this torque can be large in multilayers in which both spin Hall and Rashba torques are negligible. Furthermore, we demonstrate the operation of a spin torque nano-oscillator driven by this SOT. These findings significantly expand the class of materials that exhibit giant SOTs.